The information came from United States General Accounting Office reports, a February 1998 follow-up report from the White House Commission on Aviation Safety and Security, and opinions expressed at congressional hearings and in interviews. The analysis revealed that actions taken by the Federal Aviation Administration (FAA) include the installation of improved technology for explosives detection, the development of a passenger profiling system that potentially can be used to select some passengers for additional security procedures, and the expansion of passenger bag matching to more airports. Additional actions include the development a proposed regulation that would extend existing employment background and criminal history check requirements to screeners, their supervisors, and others who perform security duties associated with baggage or cargo and a draft rule on screener company certification. The FAA has also proposed prohibitions against tampering or interfering with airport security systems, requirements that all airports maintain a proprietary security program that the FAA has approved, and an identification system in each airport to control access to sensitive and high-security areas. The FAA is also increasing its tests of airport and air carrier security measures, increasing the number of field inspectors, and developing a standardized model for conducting airport vulnerability assessments. Most of these steps toward aviation security have met with enthusiasm, but critics note several problems and private industry would prefer that the FAA move away from its standardized approach.